docs(authentication): simplify code excerpt to obtain token

This template supports token authentication only.

Tokens associated with OpenShift user accounts are only valid for 24 hours.

To generate a token that never expires you need to create a new [service account](https://docs.openshift.com/container-platform/latest/authentication/understanding-and-creating-service-accounts.html).

To generate a token that never expires you need to [create and use a service account token](https://docs.openshift.com/container-platform/latest/nodes/pods/nodes-pods-secrets.html#nodes-application-secrets-creating-using-sa_nodes-pods-secrets).

Follow these steps:

```bash

oc create serviceaccount cicd

oc policy add-role-to-user <role_name> system:serviceaccount:<your_project_name>:cicd -n <your_project_name>

# below command displays `serviceaccount-token-name` (ex: cicd-token-l9tdx)

oc get secrets --field-selector type=kubernetes.io/service-account-token -n <your_project_name> | grep cicd | head -1 | cut -d " " -f 1

# use this `serviceaccount-token-name` to get secret with jq

oc get secret <serviceaccount-token-name> -o json -n <your_project_name> | jq -r .data.token | base64 -d

# create a service account

oc create serviceaccount cicd -n <your_project_name>

# ⚠ don't forget to add required role(s) (ex: basic-user & edit)

oc adm policy add-role-to-user <role_name> system:serviceaccount:<your_project_name>:cicd -n <your_project_name>

# retrieve service account's token name(s)

oc describe serviceaccount cicd -n <your_project_name>

# get service account token from the secret

oc describe secret <token_name> -n <your_project_name>

# test the token

oc get all --token=<token>

# this token can be used to authenticate ;)

```

:warning: don't forget to replace `<your_project_name>` with your OpenShift project name and `<role_name>` with the appropriate role (ask your OpenShift support).

:warning: don't forget to replace `<your_project_name>` with your OpenShift project name and `<role_name>` with the appropriate role (ask your OpenShift support). See [default cluster roles](https://docs.openshift.com/container-platform/latest/authentication/using-rbac.html#default-roles_using-rbac).

### Deployment context variables